This invention relates to a lubricated rotary seal disposed between a shoulder of a rotary shaft and a face plate through which the shaft end extends. More particularly, the invention provides a self-lubricating seal that has storage space for a quantity of oil which will permit proper operation of the seal over a long period of time before the replenishment of oil becomes necessary.
Numerous rotary seals for rotating shafts have been proposed and several types are used in various applications. For example, U.S. Pat. No. 2,910,329 to Runton discloses a sealing ring and thrust bearing on the shaft of a turbine rotor. Runton's seal is held between shoulder 16 of his shaft and wall 12 through which the shaft extends. The seal has sealing ring 25 which is held in contact with wall 12 by springs 21. The stated feature of Runton's invention is a sealing ring comprising woven plies embedded in thermosetting resin. The sealing ring allegedly has low-friction surface characteristics so that lubricating oil is not used.
The seal of Runton may be used in some specific applications but is not broadly applicable particularly in cases where the seal may be exposed to liquid and dirt particles or where the escape of debris resulting from the wear and erosion of the seal against a face plate might contaminate a product such as pastry dough that is rolled into a sheet between a pair of rotating shafts, each having seals at its opposite shoulders.
A principal object of this invention is to provide a lubricated rotary seal with an oil-permeable or porous bearing washer that can function for a long period of time without replenishing its oil supply.
A further object is to shield the oil-porous bearing washer from direct exposure to liquid that may contact the exterior of the rotary seal.
Another important object is to prevent or minimize the escape from the rotary seal of oily debris formed by the erosion of the face of the bearing washer.
Other features and advantages of the invention will be apparent from the description which follows.